1. Field of the Invention
The present invention relates to a slot interface access unit for accessing slot interfaces that are distributed between a plurality of main units, a method thereof and a program thereof.
The present invention also relates to a redundancy configuration of a main unit and a replacing method of a main unit, by which a plurality of main units are installed and when a main unit to be a master ceases to function properly, another main unit is operated as a substitute master main unit.
2. Description of the Related Art
There have heretofore been technologies for connecting main units over a network so that the main units can mutually use each other's functions. As employed herein, a main unit refers to an apparatus which has an interface for accommodating terminals (such as key telephones), an interface for connecting to a public line, or an interface for connecting to an IP network.    Patent Document 1: International Publication WO 1997/35255 pamphlet    Patent Document 2: JP 2001-358736-A
In order for a main unit to use the functions of other main units over the network, however, modifications have had to the respective functions. Unmodified functions are not network-compatible, and it has been impossible for all the functions of one main unit to be used by another main unit via the network.
More specifically, with conventional networking connections between the main units, the main units have managed resources by using their respective CPUs, as well as the states of terminals, lines, and the like separately. To run the functions of the main units over the network has thus been not as easy as to run them on each single main unit, and has required that the functions be modified so as to be network-compatible.
In conventional networking systems, package slots, i.e., the resources of the main units have been separately managed system by system, so that the systems have had no access to each other's resource information, conditions, and the like. This has caused a limitation in using the functions of the main units over the network.